Liquid Discharging Head Projections Reduce Satellite Droplets
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Solution Overview
Problem
Existing liquid discharging heads, such as thermal inkjet heads, suffer from the generation of satellite droplets due to surface tension and speed differences, leading to reduced recording quality as these satellite droplets often land off-target on the recording medium.
Innovation Solution
The liquid discharging head incorporates a discharge port design with projections towards its center, where the shortest interval between these projections is 5 μm or less, to quicken the separation of the main droplet and reduce satellite formation by minimizing the trailing tail, thus enhancing recording quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the resistance of the high resistance region is increased to reduce satellite droplet generation, then satellite droplet generation is reduced, but liquid discharge becomes difficult and discharge speed decreases
Solution Approach 1:
The discharge port is designed with non-uniform resistance distribution, creating a first resistance region and a second resistance region. The first region has higher resistance to reduce satellite droplet generation, while the second region has lower resistance to maintain liquid discharge speed. This local differentiation of resistance properties resolves the contradiction between reducing harmful satellite droplets and maintaining productive discharge speed.
2Object-generated harmful factors
If the discharge port is designed with a shape other than circular to reduce satellite droplets, then satellite droplet generation is reduced, but liquid discharge becomes difficult when liquid evaporates or solid components adhere
Solution Approach 1:
The discharge port incorporates distinct resistance regions with different surface characteristics. The first resistance region has higher resistance to minimize satellite droplet formation, while the second resistance region has lower resistance to prevent liquid adhesion and evaporation issues. This localized differentiation maintains discharge reliability while reducing satellite droplet generation.
Solution Approach 2:
The invention changes the resistance parameter distribution within the discharge port by forming specific surface patterns. This creates zones with different resistance values, allowing the discharge port to simultaneously reduce satellite droplet generation (through high resistance regions) and maintain reliable liquid discharge (through low resistance regions), thereby resolving the reliability issue.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively reduces the generation of satellite droplets, improving the precision and quality of liquid discharge by shortening the separation time and reducing the size of satellite droplets, ensuring that the main droplet lands accurately on the recording medium.
Implementation Method 1
A heating resistance element (heater) is formed in the pressure chamber, and the liquid is discharged from the discharge port by using discharge energy (heat) generated by the heating resistance element.
Implementation Method 2
a thermal inkjet method which adds heat to a liquid, which causes a film to boil, and which makes use of a bubbling force thereof
Implementation Method 3
The tail frequently becomes a very small liquid droplet, called a satellite droplet, as a result of being separated from the main droplet by the surface tension of the liquid that is being ejected.
Implementation Method 4
This corresponds to forming a region having high resistance and a region having low resistance in the discharge port with respect to discharge liquid droplets, and allows the generation of satellite droplets to be reduced by increasing the difference between the resistances of the two regions.
Data Source
AI summary
A liquid discharging head includes a discharge port that discharges a liquid, a pressure chamber that communicates with the discharge port, and an energy generating element that is disposed in the pressure chamber. In the liquid discharging head, the discharge port is provided with a plurality of projections that project towards a central portion of the discharge port from an inner peripheral edge of the discharge port, and an interval between the projections at a location where the projections are closest to each other is 5 μm or less.